The present invention can be widely and generally applied to the manufacture of the material of a semiconductor or an electronic device such as a semiconductor device or liquid crystal device, and will be described exemplifying the background art of the semiconductor device for descriptive convenience.
In recent years, as the integration density of the semiconductor device increases and the feature size of the semiconductor device shrinks, in the semiconductor device manufacturing process, a plasma processing apparatus is used more and more often in order to perform various types of processes such as film deposition, etching, and ashing. When such a plasma process is employed, a general advantage is obtained in that highly accurate process control can be performed in an electronic device manufacturing process.
Conventionally, as a plasma processing apparatus to generate a plasma necessary for the various types of processes described above, a CCP (Capacitively Coupled Plasma) processing apparatus and ICP (Inductively Coupled Plasma) processing apparatus have been used (see patent references 1 and 2).
Of the two types of apparatuses, in the CCP processing apparatus, usually, a process chamber is usually employed which incorporates, as an upper electrode that forms one parallel plate, an Si top plate having a shower head structure to provide a more uniformed process gas flow, and a susceptor which can apply a bias to a lower electrode serving as the other parallel plate. In the plasma processing in this case, a substrate (target object) to be processed is placed on the susceptor. A plasma is generated between the upper and lower electrodes described above. The substrate is subjected to a desired process with the generated plasma.
In the CCP processing apparatus, however, the plasma density is low when compared to those of other plasma sources, and a sufficient ion flux is difficult to obtain. Accordingly, the processing rate for the target object (wafer or the like) tends to be low. Even when the frequency of the power supply for the parallel plates is increased, a potential distribution appears within an electrode surface that constitutes each parallel plate, so that the uniformity of the plasma and/or process tends to decrease. In addition, in the CCP processing apparatus, the Si electrode consumes fast, and accordingly the COC (Cost of Consumable) tends to increase.
In the ICP processing apparatus, usually, a turn coil to which a high frequency is to be supplied is arranged on a dielectric top plate (i.e., outside a process chamber) which is located on the upper side of the process chamber. The arranged coil causes induction heating to generate a plasma immediately under the top plate. The target object is processed with the generated plasma.
In the conventional ICP processing apparatus, a high frequency is supplied to the turn coil outside the process chamber (through the dielectric top plate) to generate a plasma in the process chamber. When the diameter of the substrate (target object) increases, the process chamber needs a mechanical strength for the purpose of vacuum sealing. The thickness of the dielectric top plate must accordingly be increased, thus increasing the cost. In addition, when the thickness of the dielectric top plate increases, the power transmission efficiency from the turn coil to the plasma decreases. Therefore, the voltage of the coil must be set high.
As a result, the dielectric top plate itself tends to be sputtered to degrade the COC described above. Furthermore, fine particles generated by sputtering are deposited on the substrate to likely degrade the process performance. The size of the turn coil itself must also be increased. To supply power to such a large-size coil, a high-output power supply is required.
In the conventional plasma process, power is supplied to a plasma chamber to which a gas is supplied, so as to plasmatize the gas, thus processing the base material set in the plasma chamber. The plasma process has been designed such that uniform power is supplied particularly to the electrode to generate a spatially uniform plasma. The plasma uniformity, however, is largely influenced by the electrode shape, the structure or the like of the plasma chamber, and parameters such as the pressure and gas species. Therefore, it is difficult to obtain an even plasma distribution that matches various process conditions.
Also, it is impossible to freely change the plasma generation area or the like. For example, assume that a base material having an area substantially equal to that of the plasma generation space and a base material having an area much smaller than that of the plasma generation space are to be processed. In this case, the plasma generation space must match the area of the larger base material. When coping with the base material having the smaller area, even though most of the plasma generation area is not used, the process is generally performed using a large-area plasma.
A particle beam processing apparatus is available in which various types of particles are selectively guided from a plasma source to a process chamber to process a base material in the process chamber. In this apparatus, however, the density of the plasma source cannot be sufficiently increased under a desired pressure, and the density of the particles to be radiated cannot be increased sufficiently. It is also difficult to spatially control the particles so as to selectively irradiate a desired portion of the base material.
Another plasma processing apparatus is available in which, in order to increase the plasma generation efficiency, a plasma chamber to which a gas is supplied is connected to a plasma particle generation power supply to plasmatize the gas under the atmospheric pressure, so as to process a base material in the chamber with the plasma. This atmospheric-pressure plasma processing apparatus is advantageous in that a plasma having a higher density can be obtained more easily than with a conventional reduced-pressure plasma processing apparatus.
In the atmospheric-pressure plasma processing apparatus, however, as the pressure is high, the dynamic range of the particle acceleration/deceleration energy is narrow.
The present applicant could not find any precedent technical reference, before the application, related to the present invention other than those specified by precedent technical reference information described in this specification.    Patent Reference 1:
Japanese Patent Laid-Open No. 6-163467    Patent Reference 2:
Japanese Patent Laid-Open No. 7-058087